[linux-lvm] Maximum # of PEs Per PV

[Heinz J. Mauelshagen]

You should keep the limit of 65534 PEs per PV and 65534 in mind.
If you like to create logical volumes bigger than ~256GB in size, you
need to choose a larger PE size at volume group creation time.

If you like to extend your LVs say to 1TB in the future, you need to
do a "vgcreate -s 16m mp3 /dev/hd[f-h]1".

The 65534 constraint will probably disappear in the future.
But for now you need to live with it.

-- 

Regards,
Heinz    -- The LVM Guy --

On Wed, Jan 31, 2001 at 06:30:37PM +0100, Holger Rauch wrote:
> Hi!
> 
> A friend of mine installed three 80G disks in order to create a 240G LV
> for his file server. The machine had a 2.4.1 kernel and LVM 0.9.1beta3
> installed.
> 
> In order to create the LV, I first created primary partition of type 8e, 
> then the PVs using pvcreate: 
> 
> pvcreate /dev/hd[f-h]1
> 
> and then the volume group with vgcreate:
> 
> vgcreate mp3 /dev/hd[f-h]1
> 
> When I was trying to create a LV of 240G in size, using
> 
> lvcreate -n fjdb -L 240G mp3
> 
> I got a message telling me that I may only use a certain number of
> PEs (more precisely 58623; see below)
> 
> Doing a "vgdisplay -v mp3" gave me:
> 
> --- Volume group ---
> VG Name               mp3
> VG Access             read/write
> VG Status             available/resizable
> VG #                  0
> MAX LV                256
> Cur LV                1
> Open LV               1
> MAX LV Size           255.99 GB
> Max PV                256
> Cur PV                3
> Act PV                3
> VG Size               229 GB
> PE Size               4 MB
> Total PE              58623
> Alloc PE / Size       58623 / 229 GB
> Free  PE / Size       0 / 0
> VG UUID               o4Zrsk-bibt-SbCy-d15O-mi5H-vw9r-lppgBA
> 
> --- Logical volume ---
> LV Name                /dev/mp3/fjdb
> VG Name                mp3
> LV Write Access        read/write
> LV Status              available
> LV #                   1
> # open                 1
> LV Size                229 GB
> Current LE             58623
> Allocated LE           58623
> Allocation             next free
> Read ahead sectors     120
> Block device           58:0
> 
> 
> --- Physical volumes ---
> PV Name (#)           /dev/hdf1 (1)
> PV Status             available / allocatable
> Total PE / Free PE    19541 / 0
> 
> PV Name (#)           /dev/hdg1 (2)
> PV Status             available / allocatable
> Total PE / Free PE    19541 / 0
> 
> PV Name (#)           /dev/hdh1 (3)
> PV Status             available / allocatable
> Total PE / Free PE    19541 / 0
> 
> "lvdisplay /dev/mp3/fjdb" also told me that the LV is only 229G in size:
> 
> --- Logical volume ---
> LV Name                /dev/mp3/fjdb
> VG Name                mp3
> LV Write Access        read/write
> LV Status              available
> LV #                   1
> # open                 1
> LV Size                229 GB
> Current LE             58623
> Allocated LE           58623
> Allocation             next free
> Read ahead sectors     120
> Block device           58:0
> 
> After creating the file system with "mkreiserfs /dev/mp3/fjdb", the output
> of "df -k" was:
> 
> Filesystem           1k-blocks      Used Available Use% Mounted on
> /dev/hde1              2071296     99920   1866152   5% /
> /dev/hde2              4200856    504176   3696680  12% /home
> /dev/hde4             13365668   6056124   7309544  45% /usr
> /dev/mp3/fjdb        240112476     32840 240079636   0% /fjdb
> 
> Now, I've got a few questions:
> 1. Why do I only have 229GB available on this volume group instead of
> 240G?
> 2. What is the maximum number of PEs per VG? I was looking in the HOWTOs
> for LVM limits, but I could not find anything on this issue.
> 3. Why does "df -k" tell me that I nevertheless have 240G available?
> 
> Thanks in advance! Any help is greatly appreciated!
> 
> Greetings,
> 	
> 	Holger
> 
> _______________________________________________
> linux-lvm mailing list
> linux-lvm at sistina.com
> http://lists.sistina.com/mailman/listinfo/linux-lvm

*** Software bugs are stupid.
    Nevertheless it needs not so stupid people to solve them ***

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

Heinz Mauelshagen                                 Sistina Software Inc.
Senior Consultant/Developer                       Am Sonnenhang 11
                                                  56242 Marienrachdorf
                                                  Germany
Mauelshagen at Sistina.com                           +49 2626 141200
                                                       FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-